SEATTLE, Wash. — So much for any “what if” scenario for the derailment of tanker cars carrying volatile crude oil through Seattle or elsewhere in Washington state. Five of a train’s 102 cars went off the track July 24 under the Magnolia Bridge as the train traveled at less than 5 mph. Three of the five cars carried crude oil from Bakken, N.D. Nearly 100 of the cars were transporting the potentially explosive contents.